1. Field of the Invention
The present invention generally relates to relates to a vacuum forming apparatus and a vacuum forming method for creating a vacuum between a resin sheet and a forming die by utilizing an air pressure difference on the front and back surfaces of the resin sheet to form the resin sheet into a shape.
2. Background Information
Vacuum forming apparatuses are known that pinch a heat-softened resin sheet between a forming die and a pressing device by creating a vacuum between the resin sheet and the forming die such that the resin sheet adheres closely to the forming die. For example, such a vacuum forming apparatus is disclosed in Japanese Laid-Open Patent Publication No. 2001-138389.
In order to prevent wrinkles from developing in the resin sheet, the vacuum forming apparatus of Japanese Laid-Open Patent Publication No. 2001-138389 holds two opposite sides of the resin sheet with a pair of clamps and then moves the clamps closer together before pinching the resin sheet between the forming die and the pressing device. As a result, the heat-softened resin sheet can be made to sag in a loose fashion before the forming die and the pressing device are pressed together.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vacuum forming apparatus. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.